In certain usages, the need for making inexpensively semiconductor devices and systems using these devices is greater than the need for production methods giving the highest quality of semiconductor devices. For example, certain switches can be made from majority carrier semiconductor devices, on material which has more impurities and defects than is tolerable in the best minority carrier devices. That is, as is well known, a minority carrier device requires injection of carriers, e.g., electrons in p-type material, above the equilibrium amount where they would normally not be. If defects are present in sufficient amounts, these injected minority carriers do not survive. However, in majority carrier devices, injection of carriers above equilibrium amounts is not used, so that the presence or absence of defects is of much less importance. The majority carrier devices are attractive, however, only if they can be made at reduced cost.
One approach in manufacturing semiconductor devices is to vapor deposit polysilicon onto a substrate and convert the polysilicon into recrystallized silicon. Such an approach, however, requires deposition temperatures of about 1400.degree. C. For the process to be inexpensive, and therefore useful in making inexpensive majority carrier devices, the substrate must be able to withstand such high temperatures while at the same time itself be selected from inexpensive materials. Because high temperature resistance generally requires the substrate to comprise less conventional, expensive materials, a dilemma has existed in attempts to use such inexpensive substrates. For example, high temperature resistance generally requires the use of refractory materials, such as quartz, ceramics or specialized glass, and such materials do not lend themselves to inexpensive manufacturing.
Prior to this invention a substrate comprising an organic polymer has not been described for use with semiconductor devices requiring processing at or above the noted temperature. Such a substrate has not been thought to be operable under such temperatures, since the organic polymer generally cannot tolerate such heat. Metal electrodes, although described heretofore as being sandwiched between various substrates and semiconductor layers, have not been part of the substrate itself.